The trend is for memories in computer systems to continue increasing in size to accommodate more and larger programs and data bases.
Current computer systems commonly execute programmed instructions having real or virtual addresses with a size of 32 bits or under, commonly 16, 20, 24 and 31 bits. When such virtual addresses are used, they are often translated to a real or absolute address having a 32 bit size or less. An absolute address is a real address which has been prefixed to enable multiple processors to share the same memory.
Extending the address size increases complications in a computer's addressing system. Some techniques add more complications than other techniques. One complication is to maintain downward programming compatibility after extending the address. Examples of prior patents attempting to increase address size are U.S. Pat. No. 4,675,809 to Omada et al U.S. Pat. No. 4,825,358 to Letwin and U.S. Pat. No. 4,868,740 to Kagimasa et al. None of these prior patents discloses the address-extension method of the subject invention for enabling the use of very large system memories by providing unique ways of generating real address extenders.